Vapor recovery system

ABSTRACT

A vapor recovery system is provided for recovering fuel vapors discharged from a fuel tank having a vent tube and a separate filler neck during refueling. The vapor recovery system includes a partition dividing the filler neck into an outer chamber communicable with the atmosphere and an inner chamber in fluid communication with the fuel tank. The partition includes an aperture for sealingly admitting a fuel dispensing nozzle into the inner chamber without coupling the inner and outer chambers in fluid communication during refueling. A fuel cap may sealingly engage the filler neck to close the mouth of the filler neck. A refueling sensing system is provided for actuating a flow valve during an initial stage of each refueling activity to permit flow of fuel vapor to the canister. Upon removal of the fuel cap, fuel vapor discharged from the fuel tank is conducted automatically to the canister for processing therein instead of being discharged directly into the atmosphere. Illustratively, the refueling sensing system is included in the fuel cap.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to vehicle emissions control, and particularly toa refueling vapor recovery system designed to capture, store, andsubsequently purge the fuel vapors that are displaced and generatedduring a typical vehicle refueling operation.

polluting emissions are released into the atmosphere during each andevery motor vehicle refueling activity. Typically, removal of a fuel cappermits pressurized fuel vapors present within the vehicle fuel systemto escape to the atmosphere. In view of the frequency of vehiclerefueling activities, it will be appreciated that a significant quantityof otherwise combustible fuel is lost to the atmosphere each time avehicle is refueled.

New fuel vapors are generated during refueling due to splash andagitation of the dispensed fuel, as well as from potential temperaturedifferences between the fuel tank and the dispensed fuel. In addition,as the liquid fuel dispensed at the pump fills the vehicle fuel tank,fuel vapors that are present in the tank and generated during refuelingare displaced by liquid fuel. These displaced fuel vapors are moved outof the fuel tank vapor space by the displacing action of the liquidfuel. In conventional vehicle fuel systems, these displaced vapors arereleased directly into the atmosphere via the fuel tank filler neck andare a contributing factor to air pollution.

One object of the present invention is to provide an emissions controlsystem for advantageously capturing fuel vapors normally dischargedduring a vehicle refueling activity so as to reduce waste of fuel energyresources, assist in reducing the level of air pollution, and avoid theshortcomings of conventional vehicle fuel systems.

Another object of the present invention is to provide a fuel vaporrecovery system that conforms to all government environmental and safetyregulations regarding evaporative and refueling emissions, exhaustemissions, and vehicle impact, and that also satisfiescustomer-perceived vehicle functions such as drivability, ease ofrefueling, and control of fuel vapor odor.

According to the present invention, a vapor control system includespartition means for sealing a fuel dispensing nozzle to a fuel tankfiller neck during refueling to prevent loss of fuel vapor to theatmosphere and separator means for separating liquid fuel entrained inthe fuel vapor from fuel vapor discharged from the fuel tank via afill-limiting vent tube. Preferably, the partition means divides thefuel tank filler neck into separate sealed inner and outer chambers andis configured to admit a fuel-dispensing nozzle into the inner chamberwithout coupling the inner and outer chambers together in fluidcommunication during refueling. Vapor recovery means is provided forselectively processing fuel vapor discharged from the separator mean toreduce environmentally hazardous emissions without dischargingunprocessed fuel vapor to the atmosphere during refueling.

In preferred embodiments, the vapor recovery means selectively deliversfuel vapor discharged from the separator means to a carbon canister orother vapor condenser positioned elsewhere in the vehicle, therebyreducing the mass of fuel discharged into the atmosphere duringrefueling. The vapor recovery means includes actuation means in a vaporflow passage for automatically moving a refueling control valve, whichvalve is normally spring-biased to its passage-closing position, to itspassage-opening position. This permits fuel vapor discharged from thefuel tank during each refueling activity to be conducted to the canisterfor liquid fuel recoverY treatment therein prior to being discharged tothe atmosphere. Preferably, the actuation means includes means forsensing the beginning of a vehicle refueling activity cycle.

A fuel cap is provided for closing and sealing the mouth of the fueltank filler neck. In preferred embodiments, sufficient loosening of thefuel cap on the filler neck actuates the refueling control valve toinitiate a vapor recovery sequence without breaking the vapor sealprovided by the fuel cap or otherwise permitting untreated fuel vapor tobe discharged directly into the atmosphere. The sensing means includes acontrol pad movable relative to the filler neck between positions inclose proximity to the mouth of the filler neck. Illustratively, thecontrol pad is spring-biased against the fuel cap whenever the fuel capis mounted on the filler neck. Illustratively, a mechanical linkage isprovided for moving the refueling control valve to its passage-openingposition in response to spring-biased movement of the control pad duringremoval of the fuel cap. In this way, fuel vapor discharged from thefuel tank is conducted automatically to a fuel vapor treatment site suchas a canister instead of being discharged directly into the atmospherethrough the filler neck mouth.

Also in preferred embodiments, the vapor control system further includesa safety pressure-relief valve for exhausting fuel vapor discharged fromthe separator means directly to the atmosphere during disablement of thevapor recovery means. Any pressurized fuel vapor in excess of designlimits is vented to the outer chamber for discharge to the atmospherewhenever vapor flow exceeds the capacity of the system. Preferably, thepressure-relief valve is a "whistle" valve. In other words, this valveis configured to issue a sonic warning to a refueling attendant wheneverthe pressure-relief valve is activated so that necessary correctiveaction can be taken to repair flow blockage in the system.

Additional objects, features, and advantages of the invention willbecome apparent to those skilled in the art upon consideration of thefollowing detailed description of preferred embodiments exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIpTION OF THE DRAWINGS

The detailed description particularly refers to the accompanying figuresin which:

FIG. 1 is a block diagram of a system for recovering vapors during avehicle refueling activity in accordance with the present invention;

FIG. 2 is a perspective view of an impact shield for use in protecting aportion of the system of the present invention;

FIG. 3 is an exploded perspective view of a preferred embodiment of avapor recovery module in accordance with the present invention withportions broken away;

FIG. 4 is a longitudinal sectional view taken along lines 4--4 of FIG. 3showing a fuel cap mounted on a fuel tank filler neck in afully-tightened position during normal non-refueling activities;

FIG. 5 is a view similar to the view in FIG. 4 showing the fuel cap in aslightly loosened position during an initial stage of fuel vaporrecovery; and

FIG. 6 is a longitudinal sectional view taken along lines 6--6 of FIG. 3showing a fuel-dispensing nozzle in phantom lines inserted into the fueltank filler neck during refueling.

DETAILED DESCRIpTION OF THE DRAWINGS

Referring to FIG. 1, one preferred embodiment of a vapor recovery system10 includes a fuel tank 12 having a filler neck 14, a fill-limiting venttube 16, and a vent valve opening 18, a vapor recovery module 20, and aroll-over valve module 22. The vapor recovery module 20 is automaticallyactuated in the manner explained below to conduct substantially all fuelvapors that are present in the vapor space 24 of the fuel tank 12,displaced by liquid fuel during refueling, and generated duringrefueling, to a fuel vapor treatment site 26 for environmental treatmenttherein. preferably, a conventional charcoal canister or other vaporcondenser is provided at treatment site 26 to adsorb liquid fuelentrained in the recovered fuel vapors onto a substrate to permitrecombustion in vehicle engine 27 at a later time.

In the embodiment of FIG. 1, the roll-over valve module 22 includes aroll-over valve 28, a tank-pressure control valve 30, a vapor-reliefvalve 32, and a constant flow valve 34. The roll-over valve module 22 ispreferably mounted in a wall of the fuel tank 22 at vent valve opening18. The roll-over valve module 22 serves a dual purpose by selectivelyreleasing fuel vapors from the vapor space 24 to either the canister 26or the atmosphere so as to regulate flow of fuel vapors to the canister26, and by automatically closing the vent valve opening 18 during avehicle rollover accident so as to guard against hazardous fuel leakage.Reference is hereby made to a U.S. Pat. No. 4,655,238 to Szlaga for acomplete disclosure of a roll-over valve assembly suitable for use inthe vapor recovery system 10.

As shown in block diagram form in FIG. 1, the vapor recovery module 20includes a partition 40 in the filler neck 14, a vapor-liquid separator42, a refuel control valve 44, an actuating linkage 46, a safety valve48, and a fuel cap 50. Illustratively, the actuating linkage 46 providesmeans for sensing whenever the fuel cap 50 is loosened a sufficientamount during an initial stage of each refueling activity. The actuatinglinkage 46 also provides means for actuating the refuel control valve 44in response to the sensing means. Actuation of refuel control valve 44permits fuel vapors present in the vapor space 24, and otherwiseassociated with refueling, to be conducted to the canister 26 via avapor flow path in the vapor recovery module 20 instead of allowing suchenvironmentally damaging vapor to escape untreated to the atmospherethrough filler neck outlet 54. FIGS. 3-6 illustrate one preferredarrangement of the components illustrated in block diagram form in FIG.1.

Referring primarily to FIGS. 1 and 6, partition 40 is staked in place inthe filler neck 14 in proximity to the filler neck mouth 54 to separatefiller neck 14 into an outer chamber 56 and an inner chamber 58. Theouter chamber 56 is communicable with the atmosphere via filler neckmouth 54 whenever the fuel cap 50 is removed. The inner chamber 58 isalways in fluid communication with the fuel tank 12 via the filler neck14. Advantageously, partition 40 provides a vapor tight inner chamber 58so as to prevent escape of untreated fuel vapors to the atmosphereduring refueling.

At service, partition 40 may be easily detached for repair or disposal.As shown in FIG. 6, the inner diameter of outer chamber 56 is stepped topermit removal of the partition 40 therethrough. One advantage of thepresent invention is that partition 40 is replaceable as a unit forservice through the outer chamber 56 and filler neck mouth 54 withoutdisassembly of the vapor recovery module 20 from its installed positionin a vehicle. After service, a repaired or replacement partit:on may bestaked into a proper position within filler neck 14.

partition 40 includes a nozzle size-restricting passageway 60 foradmitting a pump nozzle (represented by broken lines in FIG. 6) into theinner chamber 58. An annular nozzle seal 62 sealingly embraces the pumpnozzle durinq pumping as shown in FIG. 6. Annular nozzle seal 62 is heldin sealinq position in the passageway 60 by retainer 64 so that fuel canbe dispensed into the inner chamber 58 without coupling the inner andouter chambers 58, 56 in fluid communication during refueling. Hardnozzle pilot surface 61 is provided in passageway 60 to protect seal 62from damage during refueling. An O-ring seal 66 is situated in a recessformed in an exterior wall of partition 40 to engage an interior wall ofpassageway 60 in sealing relation. Leaded fuel splash door 68 ispivotally mounted or otherwise deflectable in relation to an inner endof partition 40 in a customary way to splash leaded fuel dispensed usingan ordinary pump nozzle back toward a user.

Vapor-liquid separator 42 is used for separating liquid fuel entrainedin fuel vapor discharged from fuel tank 12 via a fill-limiting tube 16and/or a filler neck 14 to reduce the mass of fuel entrained in suchdischarged vapor prior to introducing the vapor into canister 26. Asshown best in FIG. 3, the separator 42 includes a hollow base 70 fixedto an exterior surface of filler neck 14 and a top cover assembly 72.

Referring to FIGS. 3 and 6, base 70 includes an inlet 74 in fluidcommunication with the fill-limiting vent tube 16 via pipe 76, a liquidfuel outlet 77, and an upper opening 78 coverable by top cover assembly72. Annular shield 80 is installed in the chamber provided by hollowbase 70 in spaced relation to define an annular swirl passage 82therebetween. The top cover assembly 72 includes a discriminator screen84, a fuel vapor outlet 86, and a pressure-relief outlet 88. Thediscriminator screen 84 depends therefrom so that it is suspended in aninterior space 90 of annular shield 80 when the top cover assembly 72 ismounted on the hollow base 70.

In use, fuel vapor introduced into separator 42 is swirled through swirlpassage 82 causing liquid fuel (represented by broken line arrows inFIGS. 3 and 6) entrained in the fuel vapor to move downwardly toward theliquid fuel outlet 77 while the remaining lower density fuel vapor(represented by solid line arrows in FIGS. 3, 5, and 6) moves upwardlytoward the fuel vapor outlet 86. The discriminator screen 84 interceptsthe swirling fuel vapor so that some of the liquid fuel entrained in thevapor coalesces or otherwise agglomerates thereon to form liquid fueldroplets that once formed fall under gravity toward liquid fuel outlet77. Fuel vapor outlet 86 is coupled to refuel control valve 44 by pipe92 and pressure-relief outlet 88 is coupled directly to safety valve 48.In addition, liquid fuel outlet 77 is coupled to inner chamber 58 of thefiller neck 14 to provide means for recovering separated liquid fuel byrecirculation of same to the fuel tank 12 via filler neck 14.

Refuel control valve 44 regulates the flow of fuel vapor discharged fromseparator 42 to the canister 26 so that such flow is permitted onlyduring vehicle refueling activity. Referring to FIGS. 4 and 5, therefuel control valve 44 includes a valve housing 110 providingdownstream chamber 112 coupled in fluid communication to an upstreamchamber 114 by central aperture 116. As shown best in FIG. 3, the refuelcontrol valve 44 also includes a fuel vapor inlet 118 coupled to thefuel vapor outlet 86 of separator 42 via pipe 92 and fuel vapor outlet120 coupled to canister 24 via pipe 122.

A primary valve head 124 is provided in upstream chamber 114 for closingcentral aperture 116 during all period of non-refueling activity toprevent unwanted distribution of fuel vapor from separator 42 to thecanister 26. Valve stem 126 extends in substantially spaced-apartparallel relation to filler neck 14 from a downstream face 128 of valvehead 124 through a bearing support 130 provided in end wall 132 of valvehousing 110 toward the filler neck mouth 54. A secondary valve head 134is provided in downstream chamber 112 and rigidly attached to valve stem126 for movement therewith.

The primary valve head 124 is normally loaded to its shut-off positionclosing aperture 116 by each of biasing springs 136, 138 as shown bestin FIG. 4. primary biasing spring 136 acts between fixed end wall 140and movable primary valve head 124 while secondary biasing spring 138acts between fixed central wall 142 and movable secondary valve head134. It will be appreciated that such a dual-spring arrangementadvantageously ensures substantially fail-safe operation of refuelingcontrol valve 44 in that the primary valve head 124 will remain in itsnormally closed shut-off position even if one of springs 136, 138 shouldfail.

Actuating linkage 46 provides one preferred means for actuating therefueling control valve 44 during a predetermined initial stage of eachrefueling activity. In the illustrated embodiment, a mechanicalspring-biased linkage is provided for sensing when fuel cap 50 isloosened from its mounted position on the filler neck 14, whichloosening is indicative of the beginning of a refueling activity cycle,and for then moving the primary valve head 124 in opposition to biasingsprings 136, 138 to an aperture (116)-opening position. Once aperture116 is opened, fuel vapors can flow therethrough from the vapor-liquidseparator 42 to the canister 26 during refueling. It will be appreciatedthat various hydraulic, pneumatic, electrical, and mechanical sensoryswitching systems could form analogs of the preferred mechanicalactuating linkage 46 illustrated in FIGS. 3-6 without departing from thepresent invention.

One important feature of the present invention is that the vaporrecovery module 20 is activated automatically or at least remotelycontrolled to recover fuel vapor for later recombustion whenever thevehicle is ready for refueling. It is within the scope of the presentinvention to actuate said linkage means by a manner other than looseningof a fuel cap. For example, actuating linkage 46 could be coupled to afuel door, fuel pump nozzle, control button, or other similar member topermit a refueling attendant to actuate the refueling control valve 44in a variety of different ways at a preferred moment during eachrefueling activity cycle.

Referring to FIGS. 3-6, actuating linkage 46 includes an annular controlpad 150, pad-biasing springs 152, control rods 154, control ring 156,and pivoting yoke lever 158. As shown best in FIGS. 4-6, control pad 150is positioned in outwardly-facing annular groove 160 formed in refuelingcavity wall 162 in a region surrounding the mouth 54 of the filler neck14. A plurality of control rods 154 extend from control pad 150 throughcompanion rod-receiving apertures 164a,b formed in the refueling cavitywall 162 and control ring 156, respectively, into engagement withannular groove 166 formed in control ring 156 as seen in FIGS. 4 and 5.A pad-biasing spring 152 surrounds each control rod 154 to bias thecontrol pad 150 normally from the inactive popsition shown in FIG. 4 tothe valve-actuating position shown in FIG. 5. Although spring 152 isshown in annular groove 160 in FIGS. 4 and 5, it is expected that such aspring could alternatively be positioned elsewhere, e.g., in contactwith control ring 156. Yoke lever 158 is mounted for pivotal movementabout a vertical pivot axis at pivot 168. In the illustrated embodimentbest seen in FIGS. 1, 4, and 5, yoke lever 158 includes a central leverarm 170 for contacting a distal end of valve stem 126 and a pair ofoppositely-extending outstretched lever arms 172 for engaging thecontrol ring 156. In particular, as best seen in FIG. 6, projections 174on lever arms 172 engage a radially-outwardly facing channel 176 formedon an outer edge of control ring 156 to interconnect lever arms 172 andcontrol ring 156.

The safety valve 48 is illustrated in FIGS. 1, 3, and 5 and includes anormally closed poppet valve 194 and biasing means 196 for yieldablybiasing the poppeet valve 194 from an open venting position (not shown)to its normally closed position. The poppet valve 194 is moved againstthe yieldable biasing means 196 whenever the pressure in a vapor flowpassage 16, 70, 76, 92, 110, and 122 coupling the fuel tank 12,vapor-liquid separator 42, refuel control valve 44, and vapor treatmentsite 26 in fluid communication exceeds a predetermined thresholdpressure level. In addition, the safety valve 48 is configured to issuea sonic warning to a refueling attendant during exhaustion to theatmosphere via pipe 94, outlet opening 198, and outer chamber 56 of thefuel vapor discharged from the vapor-liquid separator 42 via the openpoppet valve 194. Thus, the safety valve 48 is designed to provide abypass conduit around the sealed partition 40 to provide a means fordischarging fuel vapor to the atmosphere during refueling in the eventthe refuel control valve 44, actuating linkage 46, or other component isdisabled due to malfunction.

In operation, loosening of fuel cap 50 allows control pad 150 to beurged by spring 152, to the right of its position shown in FIG. 4 towardits valve-actuating position shown in FIG. 5. At the same time, controlrods 154 pull control ring 156 also to the right causing yoke lever 158to pivot in a clockwise direction about its pivot axis 168, pushing thedistal end of valve stem 126 to the left of its position shown in FIG.4, thereby causing valve heads 124, 134 to compress springs 136, 138,respectively. Such movement opens valve head 124 permitting fuel vaporto be conducted therethrough to the canister 26 in response to looseningof the fuel cap 50. It is envisioned that fuel cap 50 threadedly engagesthe filler neck 14 at its mouth 54 so that fuel cap 50 may be loosenedsimply by rotation. Seal 178 is provided between filler neck cap 14 andfuel cap 50 to seal outer chamber 56 at its outermost end 54 as shownbest in FIGS. 4 and 5.

Fuel cap 50 provides suitable means for actuating control pad 150 tovent vapor through the refueling control valve assembly 44 withoutprematurely breaking the seal provided by seal 178. Thisseal-maintaining function could be accomplished in a number of differentways. Preferably, fuel cap 50 includes a lost-motion feature so that acontrol pad-activating grip portion 180 of fuel cap 50 is movablerelative to an inner seal-maintaining portion 182 also of the cap 50during the initial stages of every refueling activity. Thus, therefueling attendant can rotate grip portion 180 a sufficient amount,desirably about one-half of a full turn, to release the outwardly biasedcontrol pad 150 without rotating seal-maintaining portion 182, whichrelease could result in prematurely breaking the seal provided by seal178.

Referring to FIGS. 2 and 3, refueling module impact shield 184 isprovided for mounting to interior plate 183 within the vehicle interiorto protect exposed portions of vapor recovery module 20. The impactshield 184 includes a shield housing 186 provided with peripheralmounting flange 187. The impact shield 184 is formed to includeapertures provided with fill, fill-limit, and canister connections andis constructed of a high impact nylon material or the like to protectsensitive components of vapor recovery module 20.

In another embodiment (not shown) of the system shown in FIG. 1, it iscontemplated that roll-over valve module 22 be incorporated directlyinto the structure of the vapor recovery module 20. In one arrangement,this could be accomplished bY coupling (not shown) in fluidcommunication the fuel vapor inlet port of roll-over valve 28 to fuelvapor outlet 86 of vapor-liquid separator 42 instead of being coupled influid communication to fuel tank vapor space 24 via vent valve opening18. It will be appreciated that various components of the roll-overvalve module 22 could be included, either individually or incombination, in various locations within the network of the vaporrecovery module 20 without departing from the scope of the presentinvention.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe scope and spirit of the invention as described and as defined in thefollowing claims.

What is claimed is:
 1. A system for recovering fuel vapors dischargedfrom a vehicle fuel system during refueling, the vehicle fuel systemincluding a fuel tank having a vent tube and a separate filler neck, thesystem comprisingpartition means for dividing the filler neck into anouter chamber communicable with the atmosphere and an inner chamber influid communication with the fuel tank, the partition means includingaperture means for sealingly admitting a fuel dispensing nozzle into theinner chamber without coupling the inner and outer chamber in fluidcommunication during refueling, separator means for separating liquidfuel entrained in the fuel vapor from fuel vapor discharged from thefuel tank via at least one of the vent tube and filler neck, and vaporrecovery means for selectively processing vapor discharged from theseparator means at a fuel vapor treatment site without discharging vaporthrough the outer chamber of the filler neck to the atmosphere duringrefueling.
 2. The system of claim 1, further comprising, liquid fuelrecovery means for conducting separated liquid fuel to the inner chamberof the filler neck for delivery to the fuel tankk.
 3. The system ofclaim 1, wherein the separator means includes a container having a fluidentry port, a vapor exit port, a liquid fuel exit port, means forcausing liquid fuel entrained in the fuel vapor to move downwardlytoward the liquid fuel exit port while the lower density fuel vapormoves upwardly toward the vapor exit port.
 4. The system of claim 3,wherein the separator means further includes means for defining acircular path through which the fuel vapor moves after entering saidentry port, the path defining means including a radially outer wallagainst which the fuel vapor is centrifugally forced.
 5. The system ofclaim 1, further comprising safety valve means for exhausting fuel vapordischarged from the separator means to the atmosphere during disablementof the vapor recovery means due to malfunction.
 6. The system of claim5, wherein the safety valve means provides sonic means for issuing anaudible warning to a refueling attendant during exhaustion to theatmosphere of said discharged fuel vapor.
 7. A system for recoveringfuel vapors discharged from a vehicle fuel system during refueling, thevehicle fuel system including a fuel tank having a vent tube and aseparate filler neck, the system comprisingpartition means for dividingthe filler neck into an outer chamber communicable with the atmosphereand an inner chamber in fluid communication with the fuel tank, thepartition means including aperture means for sealingly admitting a fueldispensing nozzle into the inner chamber without coupling the inner andouter chambers in fluid communication during refueling, separator meansfor separating liquid fuel entrained in the fuel vapor from fuel vapordischarged from the fuel tank via at least one of the vent tube andfiller neck, vapor recovery means for selectively processing vapordischarged from the separator means without discharging vapor throughthe outer chamber of the filler neck to the atmosphere during refueling,vapor delivery means for conducting fuel vapor discharged from theseparator means to a fuel vapor treatment site, and control means forregulating the flow of fuel vapor conducted by the vapor delivery means.8. The system of claim 7, wherein the vapor recovery system furtherincludes a vapor-condensing canister at the fuel vapor treatment site.9. The system of claim 7, wherein the vapor delivery means includes avapor flow passage, and the control means includesa valve movable withinthe vapor flow passage between a passage-closing position and apassage-opening position, spring means for yieldably urging the valvenormally to its passage-closing position during non-refueling activity,sensing means for providing an actuation instruction indicative of thebeginning of a vehicle refueling activity cycle, and actuation means forautomatically moving the valve against the spring means to itspassage-opening position in response to an actuation instruction fromthe sensing means so that fuel vapor discharged from the fuel tankduring each refueling activity cycle is conducted to the fuel vaportreatment site for liquid fuel recovery treatment therein before beingdischarged to the atmosphere.
 10. The system of claim 9, furthercomprising safety valve means for exhausting fuel vapor discharged fromthe separator means directly to the atmosphere whenever the valve issubstantially immovable from its normal passage-closing position duringa refueling activity cycle due to malfunction of at least one of thesensing means and the actuation means.
 11. The system of claim 9,wherein the actuating means is a filler neck closure mountable on thefiller neck to cover the mouth of the filler neck in sealing relation,the filler neck closure includingfirst stage means for inducing thesensing means to provide the actuation instruction without disruptingsealing engagement of the closure and the filler neck, and second stagemeans for subsequently breaking sealing engagement of the closure andthe filler neck to permit removal of the closure from the filler neckduring a refueling activity.
 12. The system of claim 11, wherein thefiller neck closure is rotatably mountable on the filler neck andincludes means for activating the first and second stages in sequence inresponse to rotation of the closure from sealing engagement with thefiller neck toward a closure-removal position.
 13. The system of claim9, further comprising pressure relief means for discharging fuel vaporfrom the vapor delivery means to the atmosphere during disablement ofthe control means due to malfunction, the pressure relief means havingan inlet in fluid communication with a section of the vapor flow passageintermediate the separator means and the movable valve of the controlmeans, an outlet in fluid communication with the inner chamber in thefiller neck, and a vapor-conducting passageway extending therebetween.14. The system of claim 13, wherein the pressure relief means furtherincludes a normally-closed poppet valve and biasing means for yieldablybiasing the poppet valve from an open venting position to itsnormally-closed position, the poppet valve being moved against theyieldable biasing means to its open venting position whenever thepressure in the vapor flow passage section exceeds a predeterminedthreshold pressure level.
 15. The system of claim 13, wherein thepressure relief means provides sonic means for issuing an audiblewarning to a refueling attendant during exhaustion to the atmosphere ofsaid fuel vapor discharged from the separator means via the open poppetvalye.
 16. A system for capturing vapors normally discharged during avehicle refueling activity through a filler neck spout in a vehiclehaving a fuel tank, a filler neck communicating with the fuel tank andterminating at the filler neck spout, a fill-limiting vent tubecommunicating with the fuel tank, and a vapor-condensing canister, thesystem comprisingpartition means for dividing the filler neck into anouter chamber communicable with the atmosphere through the filler neckspout and a separate inner chamber in fluid communication with the fueltank, the partition means including a nozzle-receiving passagewayinterconnecting the inner and outer chambers and nozzle seal means forsealingly embracing a fuel-dispensing nozzle inserted into the innerchamber through the nozzle-receiving passageway without placing theinner and outer chambers in fluid communication during a fuel-dispensingrefueling activity, separator means for separating liquid fuel fromvapor discharged under superatmospheric pressure from the fuel tank viaat least one of the fill-limiting vent tube and filler neck, vapordelivery means for conducting vapor discharged from the separator meansto the vapor-condensing canister, the vapor delivery means includingvalve means for selectively permitting vapor flow through the vapordelivery means, the valve means being arranged normally to block theflow of fuel vapor to the canister through the vapor delivery means, anda fuel cap for sealingly closing the filler neck spout, the fuel capincluding refueling sensing means for actuating the valve means duringan initial stage of each refueling activity to permit flow of fuel vaporto the canister so that upon removal of the fuel cap fuel vapordischarged from the fuel tank is conducted automatically to the canisterfor processing therein instead of being discharged directly into theatmosphere.
 17. The system of claim 16, further comprising liquid fuelrecovery means for conducting separated liquid fuel to the inner chamberin the filler neck for delivery to the fuel tank.
 18. The system ofclaim 17, wherein the liquid fuel recovery means also conducts fuelvapor from the inner chamber of the filler neck to the separator meansfor subsequent discharge to the canister while separated liquid fuel isbeing conducted to the inner chamber.
 19. The system of claim 16,wherein the separator means includes a container having an entry port, avapor exit port, a liquid fuel exit port, and means for causing liquidfuel entrained in the vapor to move downwardly toward the liquid fuelexit port while the lower density vapor moves upwardly toward the vaporexit port.
 20. The system of claim 19, wherein the separator meansfurther includes means for defining a circular path through which thevapor moves after entering the entry port, the path defining meansincluding a radially outer wall against which the vapor is centrifugallyforced.
 21. The system of claim 19, wherein the separator means furtherincludes discriminator means for intercepting vapor in the container sothat liquid fuel entrained in the vapor coalesces thereon to form liquidfuel droplets that once formed fall under gravity toward the liquid fuelexit port.
 22. The system of claim 16, wherein the vapor delivery meansincludes a vapor flow passage, and the valve means includesa valvemovable within the vapor flow passage between a passage-closing positionand a passage-opening position, spring means for yieldably urging thevalve normally to its passage-closing position during non-refuelingactivity, and actuation means for automatically moving the valve againstthe spring means to its passage-opening position in response to aninstruction from the sensing means so that vapor discharged from thefuel tank during each refueling activity is conducted to the vaporcondensing canister for liquid fuel recovery treatment therein beforebeing discharged to the atmosphere, the actuation means including meansfor sensing the beginning of a vehicle fuel activity cycle.
 23. Thesystem of claim 22, wherein the fuel cap includes an actuationmember,the sensing means includes a movable control pad, and springmeans for yieldably biasing the control pad against the actuationmember, and the actuation means further includes linkage means forinterconnecting the control pad and the valve means so that the controlpad is urged by the spring means to actuate the valve means via thelinkage means in response to movement of the actuation member at least apredetermined distance in relation to the filler neck during removal ofthe fuel cap from the filler neck by a refueling attendant during aninitial stage of a refueling activity.
 24. The system of claim 16,wherein the vapor delivery means further includes a vapor flow passage,and the valve means includesa valve movable within the vapor flowpassage between a passage-closing position and a passage-openingposition, first spring means for yieldably urging the valve normally toits passage-closing position during non-refueling activity, a controlpad positioned in proximity to the filler neck spout and movablerelative to the filler neck between a disabled position and avalve-actuating position, second spring means for yieldably biasing thecontrol pad against a mounted fuel cap so that the control pad movestoward its valve-actuating position in response to movement of the fuelcap in relation to the filler neck, and linkage means for moving thevalve to its passage-opening position in response to spring-biasedmovement of the control pad at least to its valve-actuating position.25. The system of claim 16, further comprising safety valve means forexhausting vapor discharged from the separator means to the atmosphereduring disablement of the valve means due to malfunction.
 26. The systemof claim 25, wherein the safety valve means provides sonic means forissuing an audible warning to a refueling attendant during exhaustion tothe atmosphere of said discharged vapor.
 27. The system of claim 25,wherein the safety valve means includes an outlet opening into the outerchamber.
 28. The system of claim 25, wherein the safety valve meansfurther includes a normally-closed poppet valve and biasing means foryieldably biasing the poppet valve from an open venting position to itsnormally-closed position, the poppet valve being moved against theyieldable biasing means to its open venting position whenever thepressure in the vapor flow passage exceeds a predetermined pressurelevel.
 29. A system for recovering fuel vapors discharged from a vehiclefuel system during refueling, the vehicle fuel system including a fueltank having a vent tube and a separate filler neck, the systemcomprisingpartition means for dividing the filler neck into an outerchamber communicable with the atmosphere and an inner chamber in fluidcommunication with the fuel tank, the partition means including aperturemeans for sealingly admitting a fuel dispensing nozzle into the innerchamber without coupling the inner and outer chambers in fluidcommunication during refueling, a fuel cap for sealingly engaging thefiller neck to close the mouth of the filler neck, and vapor deliverymeans for selectively conducting fuel vapor discharged from at least oneof the vent tube and the filler neck to a fuel vapor treatment site, thevapor delivery means including a vapor flow passage, a valve movablewithin the vapor flow passage between a passage-closing position and apassage-opening position, first spring means for yieldably urging thevalve normally to its passage-closing position during non-refuelingactivity, a control pad movable relative to the filler neck betweenpositions in close proximity to the mouth of the filler neck, secondspring means for yieldably biasing the control pad against the fuel capwhenever the fuel cap is mounted on the filler neck, and means formoving the valve to its passage-opening position in response tospring-biased movement of the control pad during removal of the fuel capfrom its mounted position on the filler neck so that before completeremoval of the fuel cap, fuel vapor discharged from the neck isconducted automatically to the fuel vapor treatment site instead ofbeing discharged directly into the atmosphere through the filler neckmouth.
 30. The system of claim 29, wherein the fuel cap includes lostmotion means for releasing the control pad thereby permittingspring-biased movement of the control pad toward a valve-actuatingposition without breaking sealing engagement of the fuel cap in thefiller neck during an initial stage of fuel cap removal.
 31. The systemof claim 29, further comprising separator means for separating liquidfuel entrained in the fuel vapor from fuel vapor discharged from thefuel tank via the vent neck, the separator means being situated in thevapor flow passage intermediate the vent neck and the valve.
 32. Thesystem of claim 31, further comprising safety valve means for exhaustingfuel vapor discharged from the separator means to the atmospherewhenever the valve is substantially immovable from its normalpassage-closing position during a refueling activity cycle due tomalfunction of the vapor delivery means.
 33. A system for recoveringfuel vapors discharged from a vehicle fuel system during refueling, thevehicle fuel system including a fuel tank having a vent tube and aseparate filler neck, the system comprisingpartition means for dividingthe filler neck into an outer chamber communicable with the atmosphereand an inner chamber in fluid communication with the fuel tank, thepartition means including aperture means for sealingly admitting a fueldispensing nozzle into the inner chamber without coupling the inner andouter chambers in fluid communication during refueling, separator meansfor separating liquid fuel entrained in the fuel vapor from fuel vapordischarged from the fuel tank via the vent tube, and vapor recoverymeans for selectively processing vapor discharged from the separatormeans without discharging vapor through the outer chamber of the fillerneck to the atmosphere during refueling.